tea1611t NXP Semiconductors, tea1611t Datasheet - Page 5

• Manufacturer Part Number: tea1611t
• Description: Zero Voltage Switching Resonant Converter Controller
• Manufacturer: NXP Semiconductors

NXP Semiconductors
7. Functional description
TEA1611T_1
Product data sheet
7.1 Start-up
7.2 Oscillator
When the applied voltage at V
switch is turned on while the high side power switch remains in the non-conducting state.
This start-up output state guarantees the initial charging of the bootstrap capacitor (C
used for the floating supply of the high side driver.
During start-up, the voltage on the frequency capacitor pin (CF) is zero and defines the
start-up state. The voltage at the soft start pin (CSS) is set to 2.5 V. The CSS pin voltage
is copied to the VCO pin via a buffer and switching starts at about 80 % of the maximum
frequency at the moment V
The start-up state is maintained until V
activated and the converter starts operating.
The internal oscillator is a current-controlled sawtooth oscillator. The frequency of the
sawtooth is determined by the external capacitor C
and IRS pins.
The minimum frequency and the non-overlap time are set by the capacitor C
resistors R
The oscillator frequency is exactly twice the bridge frequency to achieve an accurate 50 %
duty factor. An overview of the oscillator and driver signals is given in
Fig 4.
Start-up
f(min)
and R
GH-SH
V
GL
DD
Rev. 01 — 7 September 2009
0
0
0
no
. The maximum frequency is set by resistor R
DD
DD
reaches the start level.
Zero voltage switching resonant converter controller
reaches V
DD
reaches the start level (13.5 V), the oscillator is
DD(init)
(see
f
and the currents flowing into the IFS
Figure
t
4), the low side power
V
V
DD(startup)
DD(init)
014aaa036
TEA1611T
Figure
f
© NXP B.V. 2009. All rights reserved.
(see
Figure
f
5.
and the
7).
5 of 18
boot
)